Mistra (Dienogest, Ethinylestradiol)

Mistra, a combined oral contraceptive, is used within the hormonal contraception pathway to prevent pregnancy.

• Prevention of pregnancy: provides reliable contraception for women of reproductive age.
• Family planning: enables controlled timing of pregnancies.
• Menstrual cycle regulation: helps achieve more predictable bleeding patterns.

• Mistra combines the progestogen dienogest with the estrogen ethinylestradiol. Dienogest binds to progesterone receptors, suppressing the mid‑cycle surge of luteinising hormone (LH) and follicle‑stimulating hormone (FSH), thereby inhibiting ovulation. Ethinylestradiol provides estrogenic activity that stabilises the endometrium and enhances negative feedback on the hypothalamic‑pituitary axis, further preventing the LH surge. The combination also thickens cervical mucus and alters endometrial receptivity, reducing the chance of fertilisation and implantation.

Mistra may cause a range of adverse reactions, varying from mild to serious.

Common Side Effects

• Nausea: mild to moderate stomach upset.
• Headache: tension‑type or migraine‑like pain.
• Breast tenderness: swelling or discomfort of the breasts.
• Irregular bleeding or spotting: changes in menstrual flow.
• Weight gain: modest increase in body weight.
• Mood changes: fluctuations in emotional state.

Serious or Rare Side Effects

• Venous thromboembolism: blood clots in deep veins.
• Pulmonary embolism: clot migration to the lungs.
• Stroke or myocardial infarction: rare cerebrovascular or cardiac events.
• Severe hypertension: sudden, high blood pressure.
• Hepatic adenoma: benign liver tumor.
• Anaphylaxis: severe allergic reaction requiring immediate medical attention.

Before prescribing Mistra, clinicians should evaluate individual risk factors and contraindications.

• Contraindicated in pregnancy: product is classified as pregnancy category X and must not be used.
• History of thromboembolic disorders: increased risk of clotting events; avoid use.
• Hypertension screening: monitor blood pressure regularly during therapy.
• Liver disease assessment: hepatic impairment may alter hormone metabolism.
• Smoking in women over 35: contraindicated due to elevated cardiovascular risk.
• Store at ambient temperature: keep below 25°C, retain original packaging, protect from moisture.

Mistra can interact with other medicines, affecting its efficacy or safety.

Major Interactions (Avoid)

• Enzyme‑inducing anticonvulsants (carbamazepine, phenytoin, phenobarbital): may reduce contraceptive effectiveness.
• Rifampin or other strong CYP3A4 inducers: may decrease hormone levels and increase risk of unintended pregnancy.
• St. John’s wort: may lower contraceptive effectiveness.

Moderate Interactions (Monitor Closely)

• Antifungal azoles (ketoconazole, itraconazole): may increase hormone levels; monitor for side effects.
• Macrolide antibiotics (erythromycin, clarithromycin): may slightly raise plasma concentrations; observe for increased adverse reactions.